The present invention relates to a colour-matching system particularly for use in matching the colour of a dental prosthesis to that of an adjacent tooth.
In this specification the term colour will be used to include the different hues, such as red, yellow, green and orange, and also different tints or shades of the various hues in which the pure hue is modified by the admixture of white and/or black pigment in varying degrees.
Although the predominant hue of natural teeth is yellow, the variations between a very pale cream and greyish brown are infinite and dental porcelains are now available in a wide variety of different colours in order to allow dental prostheses to be matched closely to the colour of adjacent teeth in a patient's mouth. This colour matching is generally effected with the aid of samples of the different coloured porcelains, each provided in the form of a tiny bead, or button, on a respective spatula-like carrier. These are placed successively in a patient's mouth, close to a tooth which will be adjacent the prosthesis when fitted, until a good colour match is found.
A problem with this known system is that the multitude of spatulas needed occupies considerable bulk and is not easy to store in a simple system which allows them to be replaced in order quickly after use. Indeed, the normal practice is for a dental surgeon to remove several spatulas from the system at a time and to put them down temporarily on any convenient surface; the spatulas inevitably get muddled and considerable time is wasted in sorting and replacement in the system after use.
A further difficulty with the use of spatulas is that they are normally stiff and opaque so that it is not easy to locate them in the patient's mouth, close enough to a tooth for colour matching, without also obstructing the light to the tooth. In this respect, the problems of lighting a patient's mouth and the effects on colour perception of even slight shadows are well known.